Author(s): Juergen Geist; Josef Knott; Joachim Pander
Linked Author(s): Juergen Geist
Keywords: Quatic biodiversity ecological effects fish mortality fish passage habitat degradation renewable energy serial discontinuity sustainable hydropower
Abstract: Hydropower use plays an important role in the expansion of renewable energies and in achieving international climate targets. Investments in hydropower plants are usually of great significance since such installations typically last for more than 50 years. In the past, expansion of hydropower often exclusively considered economic objectives, whereas recent developments increasingly integrate ecological aspects in decision-making, typically with a focus on fish protection (Geist, 2021). Particularly in light of the declines of fish populations (Mueller et al., 2018), selecting technologies that cause the least possible harm to aquatic organisms and their habitats plays a key role in expanding and modernizing hydropower plants. In recent years, there have been various new developments in hydropower technologies, which are summarized under the term ‘innovative hydropower’. Manufacturers often use the term ‘fish-friendly hydropower’, which, however, implies that installing such systems would improve fish ecology and not just reduce negative ecological effects of hydropower. Prominent innovative hydropower plants include the very low-head (VLH) turbine, the Archimedes screw turbine, the movable hydropower plant, and the shaft hydropower plant. The objective of this research project was to compare the ecological effects of various innovative and retrofitted conventional hydropower plants in a large-scale field study. The use of different corridors for downstream fish migration, direct fish injuries and mortality during hydropower plant passage as well as the impacts of the hydropower plants on habitat quality and the aquatic community composition were assessed. Here, we summarize the main findings and lessons learned from 10 years of research on innovative and conventional hydropower plants, many of which have already been published in international and open access peer-reviewed publications. Our findings show that several of the assumptions regarding the expected ecological improvements through installing innovative hydropower plants did not hold true. Depending on site-specific conditions and operation modes, some innovative plants even caused greater fish mortality and more ecological damage than conventional hydropower plants. The study results also provide important guidance on which hydropower plant types and operation modes may reduce fish damage and other negative impacts on habitats in relation to the site-specific conditions. Applying this knowledge can lead to significant ecological improvements, particularly when retrofitting existing hydropower plants (Geist et al., 2024).
Year: 2025